1. Field of the Invention
The present invention relates to a pattern inspection method and a pattern inspection apparatus in conducting an in-process inspection in a manufacturing process.
2. Description of the Related Art
Automation of various kinds of microscopy by image processing has been advanced in a manufacturing process of a semiconductor device. One of microscopes used for inspection is an optical microscope; however, an automated inspection by the optical microscope is limited to the case where an object is a circuit pattern or the like. Automation of optical microscopy of an inspection object which has a finer structure than the circuit pattern or the like has not been advanced so much. It is an actual condition where the optical microscopy is mainly performed visually by an inspector.
Although a digital camera attached to an optical microscope or a laser microscope can take an image of an inspection object as a color image, a monochrome image is often used in image processing after taking an image. However, it is known that a subtle difference among inspection objects, which is difficult to distinguish with a monochrome image, can be distinguished if a color image is used. Reference 1 is an example where a color image is used for an appearance inspection (Reference 1: Japanese Patent Laid-Open No. 2004-125434).
As described above, optical microscopy in a manufacturing process is currently mainly conducted visually by an inspector. However, a visual inspection is also desired to be automated for cost reduction by further improvement in efficiency.